Showing papers on "Nanoparticle published in 1899"
31 Dec 1899
TL;DR: In this paper, the authors show several ways not only to record but also to modify the granular meta-layers using thermal and non-thermal optical effects, including selective reshaping of silver nanoparticles under the pulsed ruby laser illumination.
Abstract: Granular films of alkali and coinage meta ls are the most popular objects for expl oring plasmonic effects. They are easy to obtain via physical vapor deposition and to study via optical means. In this contribution we show several ways not only to record but also to modify the granular meta l films using thermal and nonthermal optical effects. Keywords: metal nanoparticles, plasmon resonance, dephasing time, surface diffusion, surface morphology, laser assisted growth INTRODUCTION Granular metal films have found a numb er of applications. They are employed in surface e nhanced Raman scattering, fast and sensitive photodetection, high performance photovoltaic s, as well as in many other existing and emerging areas. Bright optical properties of granular metal films form the basis of these applications. On the other hand, optical means may be used to shape and to study granular metal films. Granular metal films obtained via physical vapor deposition comprise nanoparticles with wide size and shape distributions. This property is detrimental in some applications. Selective reshaping of silver nanoparticles under the pulsed ruby laser illumination is shown to significantly change the shape distribution. On the other hand this process may be used to reveal the homogeneous width of the plasmon resonance in the particles of definite shape otherwise hidden under the inhomogeneous broadening of the whole ensemble.
15 citations
31 Dec 1899
TL;DR: In this paper, the processes involved in nanoparticle and nanostructure formation by laser are analyzed and relative contributions of several mechanisms involved are compared, and routes of control over particle size distribution are proposed.
Abstract: The processes involved in nanoparticle and nanostructure formation by laser are analyzed. Relative contributions of several mechanisms involved are compared. First, we consider the formation of "primary" particles and discuss the difference between femtosecond and nanosecond regimes. Then, "secondary" particle/aggregate formation is discussed. In particular, attention is focused on (i) direct cluster ejection from a target under rapid laser interaction; (ii) condensation/evaporation; (iii) fragmentation/aggregation processes during cluster diffusion; (iv) diffusion, aggregation, and/or coalescence. In addition, routes of control over particle size distribution are proposed. Possibility of formation of colloidal nanoparticles with very narrow size distribution is proven numerically. The role of such parameters as ablation yield, laser wavelength and laser fluence, and surface tension are examined. Finally, controlled nanoparticle self-assembly is discussed as a potential technique for future development of nanomaterials.
5 citations